LWPES: Test May Predict Resistance to Growth Hormone

Action Points

Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.

Explain that a small study showed that children with low baseline levels of insulin-like growth factor-1 and low levels of IGF-binding protein 3 after growth hormone therapy failed to respond to IGF-1 treatment.

Note that the study was small and considered preliminary by its investigators.

In a pilot study, patients who had IGF-1 levels more than two standard deviations below the mean, and also had IGF-BP3 more than two standard deviations below the mean, did not respond to either growth hormone or IGF-1 therapy, said Oksana Lazareva, MD, of the Infants and Children's Hospital of Brooklyn at Maimonides Medical Center in New York City.

"Currently there is no model that can reliably predict response to therapy in these children," Lazareva told MedPage Today at the Lawson Wilkins Pediatric Endocrine Society.

"We realize this is a very preliminary study," said co-author Sheila Perez, MD, from the same institution.

The researchers enrolled 43 children with an average age of 9.07 years in this study. They were included if their height was more than two standard deviation below the mean, their IGF-1 level was at least two standard deviations below the mean, and they passed the standard GHRH stimulation test.

The researchers took IGF-1 and IGF-BP3 readings at baseline and then treated the cohort with 0.46 mg/kg/week of growth hormone for three to six months, subsequently measuring growth velocity. The researchers said 23 (14 boys and 9 girls) out of 43 children responded to therapy.

The nonresponders to growth hormone were initiated on 0.24 mg/kg/day of IGF-1 therapy. Perez told MedPage Today that 14 children (10 boys and four girls) responded to that therapy. These patients were defined as having moderate growth hormone insensitivity.

Five boys and one girl failed to respond to either therapy. These children were defined as having severe growth hormone insensitivity.

"We observed that the difference in IGF-1 levels after treatment with growth hormone can differentiate between groups who can benefit from growth hormone or IGF-1 therapy," Lazareva said.

While on six months of growth hormone therapy, those children who were diagnosed with moderate growth hormone insensitivity had a 0.46 standard deviation decline in levels of IGF-BP3. This was statistically different than the 2.08 standard deviation observed for those children with severe growth hormone insensitivity (P<0.05), the researcher said.

"We are going to have to develop a trial with more patients in order to see if IGF-PB3 can be used to determine who would be best to treat with these therapies," Lazareva said.

"Because the cost of growth hormone-IGF-1 therapy is so expensive, it would be helpful to find a test that can help distinguish those children who are unlikely to respond," said Surendra Varma, MD, of Texas Tech University Health Science Center in Lubbock.

"However, as the authors suggest, it is far too preliminary to know if this test can successfully identify those children who will not respond to these therapies." Varma told MedPage Today.

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